This proposal describes a research program in glutamate bioanalysis with ultrasensitivity and simultaneous temporal and spatial resolution. The following aims will be pursued in this proposal: (1) development of glutamate (glu) monitoring techniques for ultrasensitive, ultrafast, and highly selective extracellular glu detection with 0.1 um spatial resolution, (2) development of simultaneous glu and calcium determination methodologies for real-time monitoring, (3) study of glu-calcium hypothesis in ischemic stroke on a subcellular and molecular basis, (4) investigation of multiquantal glu release at single synaptic sites. These goals will be reached with significant bioanalytical development and detailed biological and biomedical studies. The proposed research will capitalize upon the group's recent advancement in nanotechnology for ultrasmall biochemical sensors and in optical detection and imaging at the single molecule level. By the completion of this study, the PI hopes to have gained significant insight into the synaptic release mechanisms and a better understanding of ischemic injury and cell death on a subcellular basis. In addition, tools will be developed to make in-vivo measurements on living samples with a level of resolution heretofore only available in the frontier of physical sciences. The ability to monitor biological events at the subcellular level will not only enable the group to test glu-calcium hypothesis in ischemic stroke and to investigate multiquantal release from single synaptic sites, but also provide new opportunities in a wide range of biomedical studies related to glu and calcium ions.